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by rzusman
Sun Apr 16, 2017 6:19 pm
Forum: General discussion
Topic: Smart irrigation system
Replies: 11
Views: 4836

Re: Smart irrigation system

The first question is: What do you want to irrigate?
A tray of flowers? A yard? A field of crops? A golf course?
by rzusman
Mon Apr 10, 2017 10:24 pm
Forum: Python
Topic: Stepper control with video playback
Replies: 6
Views: 1113

Re: Stepper control with video playback

The error is saying that your windowsize is zero (or less) in either x or y or both dimensions.
Check your code that displays the video in a window.
by rzusman
Mon Apr 10, 2017 8:15 pm
Forum: Wanted
Topic: Pi Repair
Replies: 5
Views: 2274

Re: Pi Repair

It's hard to imagine any repair shop doing this repair for less than the cost of a new Pi.

Just try it yourself, and if you break it, buy a new one.
by rzusman
Mon Apr 10, 2017 8:12 pm
Forum: Beginners
Topic: An infra red "on/off"breakout board
Replies: 2
Views: 324

Re: An infra red "on/off"breakout board

You need to use an external microcontroller that handles the power supply sequencing, and IR decoding.
by rzusman
Mon Apr 10, 2017 3:07 am
Forum: Compute Module
Topic: CM3 Boot from microSD and Save into eMMC
Replies: 7
Views: 2188

Re: CM3 Boot from microSD and Save into eMMC

You could use the CM3-lite module and 2 SD cards, with a way to select between them (some type of external circuit that selects the first to boot from, and then gives up and switches to the second if it’s not disabled in a specific time period).
by rzusman
Sun Apr 09, 2017 3:47 pm
Forum: Compute Module
Topic: CM3 Boot from microSD and Save into eMMC
Replies: 7
Views: 2188

Re: CM3 Boot from microSD and Save into eMMC

You can’t use a µSD card on a CM3 module - the pins are not brought out to the connector.
µSD is only available on the CM3-lite.
by rzusman
Fri Apr 07, 2017 1:50 pm
Forum: Compute Module
Topic: CMIO Schematics PP pins
Replies: 3
Views: 895

Re: CMIO Schematics PP pins

There’s a jumper (J4) that tells the CM what to boot from.
If the jumper is set to 1-2, then the Pi tries to boot from USB, if it’s set to 2-3, it boots from eMMC.

If you leave the jumper in the wrong position, it will never boot from eMMC.
by rzusman
Fri Apr 07, 2017 2:11 am
Forum: Automation, sensing and robotics
Topic: Complete Climate Control System
Replies: 6
Views: 1701

Re: Complete Climate Control System

Well, I do my development in C using Xcode on OS X, with a cross-complier, so it’s possible. But, it takes a significant amount of effort to set up the toolchain. As for IO, there’s a ton of resources out there. Look at Joan’s pigpio library here: http://abyz.co.uk/rpi/pigpio/ Also, WiringPi: http:/...
by rzusman
Fri Apr 07, 2017 2:03 am
Forum: Compute Module
Topic: CMIO Schematics PP pins
Replies: 3
Views: 895

Re: CMIO Schematics PP pins

I suspect that “PP” stands for “Probe Point.” For testing and debugging only.
by rzusman
Wed Apr 05, 2017 11:55 pm
Forum: Compute Module
Topic: CM3 ACT LED no longer blinking with mmc activity?
Replies: 18
Views: 4268

Re: CM3 ACT LED no longer blinking with mmc activity?

The current firmware release contains a fix for this. You can install it by running "sudo rpi-update". Note that firmware downloaded by rpi-update is less tested than full Raspbian releases, so it is wise to backup any important data before updating. Is this fix backwards-compatible with the CM1? I...
by rzusman
Sun Sep 04, 2016 2:34 am
Forum: Beginners
Topic: How to set the date and time
Replies: 3
Views: 8703

Re: How to set the date and time

You can set the date and time with the "date" command:

date -s "03 SEP 2016 13:00:00"

But, remember that the Pi doesn't have an RTC, and will reset the time at each power-off.

If you have an Internet connection, you can use NTP to set the time.
by rzusman
Tue Jul 26, 2016 5:27 pm
Forum: Off topic discussion
Topic: what happen when element got stripped of all its electrons.
Replies: 8
Views: 1647

Re: what happen when element got stripped of all its electro

If you think you are going to strip off all the electrons and collect them, leaving a bare nucleus, you are mistaken. An ion like that has a huge positive electric charge, and will immediately strip some of the electrons from it’s surrounding environment to replace the ones it has lost. The only way...
by rzusman
Wed Jul 13, 2016 11:14 pm
Forum: Beginners
Topic: Bonding a DS18B20 Sensor
Replies: 9
Views: 1634

Re: Bonding a DS18B20 Sensor

Just use epoxy, and then cover with aluminum-backed foam tape, to insulate the sensor from the environment.
I did this on my solar water heater panels, and it worked fine.
by rzusman
Sat Jul 09, 2016 11:17 pm
Forum: Advanced users
Topic: Static IP address AND dhcp
Replies: 10
Views: 3617

Re: Static IP address AND dhcp

On OS X, I use a program called "Angry IP Scanner" to find out the IP of unknown devices. You can also use the ping utility to do the same thing, if not as simply. I'm sure there are similar tools for Windows and Linux.
by rzusman
Fri Jul 08, 2016 3:29 am
Forum: Beginners
Topic: Dry ContactHelp
Replies: 4
Views: 714

Re: Dry ContactHelp

Yes, you can just wire the contacts to a port pin and ground. You then set the port to have pullup resistors turned on, and then set the port as an input. When the input goes low, you know your contacts are closed. The Pi can only output a few tens of mA on a port pin, so accidentally setting the po...
by rzusman
Fri Jul 08, 2016 3:26 am
Forum: HATs and other add-ons
Topic: Pi Power Controller Project (safe reboot anytime)
Replies: 5
Views: 2028

Re: Pi Power Controller Project (safe reboot anytime)

You need to write a small program that listens on a port pin (or I2C, although that sounds way more complicated than necessary) for the correct shutdown signal, and then issues the shutdown command. I use a 250mS square wave on a port pin to indicate that the power has failed. Then, my program does ...
by rzusman
Wed Jun 29, 2016 11:58 pm
Forum: HATs and other add-ons
Topic: Pi Power Controller Project (safe reboot anytime)
Replies: 5
Views: 2028

Re: Pi Power Controller Project (safe reboot anytime)

There are a million topics on this. Search for Pi and UPS. The typical way people shut the Pi down when the UPS activates due to a power failure is to monitor a port pin and issue a "sudo shutdown -h now" command. I'm using supercaps and a microcontroller, but there are a lot of battery-based UPS ci...
by rzusman
Wed Jun 29, 2016 7:14 pm
Forum: Bare metal, Assembly language
Topic: Sample C Code for Performance Monitor Unit in Raspberry Pi
Replies: 2
Views: 885

Re: Sample C Code for Performance Monitor Unit in Raspberry

I doubt such a thing is possible.
Why would you want to do this?

Most perfomance benchmarks use processor load or time to execute a particular task.
by rzusman
Fri Jun 24, 2016 9:39 pm
Forum: General discussion
Topic: Offline Sunrise/Sunset Database
Replies: 21
Views: 3530

Re: Offline Sunrise/Sunset Database

Try running it with Python2. BTW, all of these programs rely on knowing your lat/long and having a stable & accurate clock. So if you run offline you will need an RTC. But, you can pre-calculate the rise/set times ahead of time by putting the calculations in a loop and iterating through the entire ...
by rzusman
Thu Jun 23, 2016 11:17 pm
Forum: General discussion
Topic: Offline Sunrise/Sunset Database
Replies: 21
Views: 3530

Re: Offline Sunrise/Sunset Database

Try running it with Python2. BTW, all of these programs rely on knowing your lat/long and having a stable & accurate clock. So if you run offline you will need an RTC. But, you can pre-calculate the rise/set times ahead of time by putting the calculations in a loop and iterating through the entire ...
by rzusman
Wed Jun 22, 2016 11:33 pm
Forum: General discussion
Topic: Offline Sunrise/Sunset Database
Replies: 21
Views: 3530

Re: Offline Sunrise/Sunset Database

This code is highly portable and works perfectly:

http://stjarnhimlen.se/comp/sunriset.c
by rzusman
Mon Jun 20, 2016 7:39 pm
Forum: Troubleshooting
Topic: 3.3v logic probe?
Replies: 2
Views: 637

Re: 3.3v logic probe?

Generally, yes, they will work.

CMOS logic levels at 3.3v are within the TTL spec of 0-.8v for a LOW and 2 - 5v for a HIGH.

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